1. Field of the Invention
The present invention relates to a multi air conditioning system and a method for operating the same, and more particularly to a multi air conditioning system, which adjusts opening degrees of indoor units in a stopped state to control the optimum amount of refrigerant flowing into indoor units in an operating state, and a method for operating the multi air conditioning system.
2. Description of the Related Art
Generally, a multi air conditioning system comprises one outdoor unit, a plurality of indoor units connected to the outdoor unit, and electric valves for adjusting the amount of refrigerant entering into the indoor units.
The above conventional multi air conditioning system operates compressors in a cooling mode or a heating mode, and adjusts opening degrees of the electric valves installed in the indoor units, thus controlling the amount of refrigerant entering into the indoor units. In case that predetermined temperatures of the indoor units differ from each other, the indoor units are operated at different operating capacities so as to optimally condition air in indoor spaces, in which the indoor units are installed.
Further, when some indoor units of the plural indoor units are stopped, the opening degrees of the electric valves installed in the indoor units in a stopped state are maintained to predetermined values, and the opening degrees of the electric valves installed in the indoor units in an operating state are changed to proper values according to the operating conditions of the multi air conditioning system. Korean Patent Laid-open No. 2003-0073358 discloses the conventional multi air conditioning system in detail, and is incorporated herein by reference.
When only some of the plural indoor units are operated, the above-described conventional multi air conditioning system maintains the electric valves of those indoor units in the stopped state to have constant opening degrees regardless of the operating conditions of the overall system. Thus, the conventional multi air conditioning system is disadvantageous in that the overall system efficiency is decreased when the amount of the refrigerant flowing into the indoor units in the operating state is not proper.
That is, when the opening degrees of the electric valves of the indoor units in the stopped state are excessively high, a large amount of the refrigerant flows into the stopped indoor units whereas a small amount of the refrigerant flows into the indoor units in the operating state, thereby reducing the heating and cooling efficiency of the system.
On the other hand, when the opening degrees of the electric valves of the stopped indoor units are excessively low, the refrigerant scarcely flows into those stopped indoor units, and part of the refrigerant is trapped in heat exchangers of the stopped indoor units (particularly, in the heating mode), thereby reducing the amount of the refrigerant circulating into the refrigerant route and thus reducing the heating and cooling efficiency of the system.